Method for making additive filters



3,043,736 r METHOD FOR MAKING ADDITIVEFILTERS George P. Toney, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey I No Drawing. Filed Mar. 2, 1959, Ser. No. 796,259

11 Claims. (Cl. 156-152) This invention relates to methods for making tobacco smoke filterin-g material and elements thereof suitable for use in cigarettes, pipes, cigarette holders and cigar holders. More particularly,the invention is concerned with improvements in making filters of the kind disclosed in my appliaction Serial No. 432,931, now -U.S. Patent No. 2,881,770, of which-the instant invention is a continuation-in-part.

In my patent just reierred to, I have shown filters of substantially increased efficiency without equivalent increase in pressure drop by providing a filter which contains certain finely divided solids in the smoke channels provided by the spacing of adjacent filaments. "I further 2 device. Preferably, the carbon is continuously applied to an opened and banded'moving tow. That is to say, tow from a supply roll is opened-to debundlize the filaments and provide a larger and more uniform tow cross section, and theopened tow is spread uniformly to a much larger widthof e.g., 8 times its original width, thereby exposing substantially all of the filaments to material, i.e.

plasticizer, issuing from a dispenser adjacent which the towpasses." The carbon may be added before, simultaneously with, or after the plasticizer, preferably with or after.

Certain of the preferred methods are further illustrated in greater detail in the following examples:

Exainp'le A continuous filament tow of yarntype cellulose acehave shown in my patent that when carbon powder, particularly activated carbon powder is employed as the finely divided deposit on the filaments, unusual .efiiciency is obtained. f

In my new filters, as just referred to, it is desirable that the additive be applied in a rapid efiicient manner. Also,

the finely divided carbon is preferably sufiicientlyiadhered to the filaments so that it willnot dust ofiLJcome loose in the smokers mouth or otherwise present such type difii: culty. Accordingly, it is believed apparent that providing improved methods for making carbon containing filters of the. type just referred to represents a highly "desirable result. Atter extended investigation I have found certain improved methods for manufacturing such filters.

h This invention, therefore, has as one object an improved method for theproduction of cigarette smoke filters con? sisting of'a bundle of substantially longitudinally oriented textile filaments infused with finely divided carbonparticles. Another object is to provide methods of theclass indicated tor increasing the bonding of the particles onto the filament filter. A still further object is to, make an additive filter :which 'is capableof removing nicotine, tars and other deleterious components of cigarette smoke without oausingthesm'oke to be dry or distasteful] Another object is toprovide improved methods which'are efiicient and efiectiv'e, yet relatively economical and simple in operation. Other objects will be apparent from the pres ent specificationand claims f I 1 As referred to above'and as disclosed in mypatent concerning, in general, thefilter product, my filter product comprises a-longitudinally oriented mass of substantially lengthwise aligned filaments, the spacing of substantially all groups of adjacent filaments providing minute passages forjjs'moke therethrough, said mass carrying finely divided carbon particlea'said particles occupying positionsinand partially blocking said passages whereby a substantial por;

tion of the smoke is impinged either'on the; filaments or onthecarbon' I if 'I have. found there are certain methods which advantag'eou'sl'y'may be employed in manufacturing'my filter product. In the broader aspects of the present invention,

tate of 5 denier per filament with a total denier'of 100,- 000, and 9 crimps per inch was used. The tow was pulled from a package of tow over stationary tensioning fingers and into a tensioning device functioning to provide tow opening as the first phase of filament separation. The device employedwas of the'type employing a pair of driven rolls to place under tension-tow positioned in the ratch between the driven'rolls and a pair of retarded rolls upstream of the driven rolls. The device wasequipped with the improvedreciprocating striker as disclosed and claimed in Smith pending US. patent application Serial No; 416,010, filed March 15,- 1954, now Patent No.

2,790,208; Uponbein-g releasedfrom the nip of the positively-driven tension rollsinto a zone of relative relaxation, 'i;e.- relatively little tension, the tow bloomed through inherent forces manifested upon the'return of the tow to its original position.

The partially opened tow of several thousand cellulose acetate filaments was slowly pulled over a compressed banding device as disclosed in application Serial No. 356,

98-3, filed May 25, 1953, by Wallace T. Jackson, now Patent No. 2,737,688. The banding device momentarily spread out the fibers toa width of six inches. While the tow was in this spread condition it was sprayed with a highly agitated slurry of one part activated bone charcoal powder in five parts dimethoxyethylphthalate plasicizer.

After this; spreading and spraying treatment the tow was uniformly collected and; fed to a garniture for formreadily at-raw 15 filter tip lengths. These tips were attached byme'ansi of an adhesive tape to a standard brand" of king-size cigaretteavailable onthe retail market in'the U.S.i 'and shortened by 1-5 mm. to-compensate for the length of the filter. The cigarettes-Were smoked on a smoking machine similar in design and operation to the smoking machine described by J. A. Bradford, W. R. Har-, lad and R. Hammer in Industrial and Engineering Chemistry, Vol. 28, pp; 836-9 (1936); The collected smoke was analyzed for nicotine and tars. The results of the smoking experiment were compared with those obtained from smoking the same brand of cigarettes containfilter tips made from the same tow of cellulose acetate fibers plasticize d dimethoxyethylphthalate plasticizer before exposing them to a powder spraying 5 without the addition of carbon.

T e oi oi arette filter 1:1 15 mm.) Mg. of Mg. of Mg. of Mg. 01' YD g p tars 1 nicotine 1 tars nicotine Elasticized cellulose acetate tow -Q. 130 20 5 Acetate tow filter 125 18 Plasticized cellulose acetate tow co sin g 4% Acetate tow filter containing 9% lampblack powbone charcoal powder....'.... 108 17 der 7 V 113 15 l Obtained from collected; smrillref (g him fizlfitered cllgaigteys. N orE.-Moisture of the tobacco in each of the cigarettes equals 12.0%. No'rn.-Moisture.o t eto acco neac o t ecgare es e uas .1. fl 'I hccigarette conflaimngfche acetate tow filters had an i e cigarettes o fl n the a'cewtewwfilters had a 10 average pressuredrop of 4.0 inches; the cigarettes con average pressure drop of 3.9 inches; the cigarettes conraining thev filiers of cellulose acetate row andbone char-Q coal powder had an average pressure drop of 4.1 inches, where pressure drop is measured as inches of water pressure developed (when airispulled through the cigarettc at the rate. of 17.5 ml. per second. This method of pressure drop has been described by'G. P. Touey in Ind.

and Eng. Chemistry, vol. 2.7, page 1789 (1955).

- Example II J A loose, i.e., partially opened crimpcd continuous filament tow ofccllulose acctateyarn containing approxi mately 10,000 fibersof. 8 denier per filament; waspulled through abath containing a highly agltaced-slurryof commercially available activaredwoodcharcoal in water.

When dried, the-tow con rained 310% ofch-arcoal powder filters made-from the 8 denicrpenfilamenttow containing 7 no carbon" also smoked on che smoking machine and the collected smoke was analyzed, in the same mannor for nicotine andtars;

- wh r Pl' I abov ,j

. Noon-Moisture of tobacco in each of the cigarerfl equals 12. 3%. "fi'Ihe cigaret-t es' containing the acetate 'towfilters had an average pressure drop of- 3.7 inches; the cigarettes containingrhefilters of cellulose acetate tow andwood charcoal; powder had. an average pressure of13.9 inches,

1 g i g' mplefllr" Q o g .1 new. r e nee seine f ib-mfaeproxi matelyAOfiOO fibers of 3 .denier per filament was spread dropis measured as explained in Example raining the filters of cellulose acetate tow and lampblack powder had an average pressure drop of 4.2 inchcs,. wherc 7 pressure drop .is measured' as explained-in Examplel above.- 'For water base bonding media I'may employ awater solution of, dexurin, polyvinyl alcohol, starch, a water-t soluble cellulose derivarive, waier-soluble natural gums,

sugars, melamine formaldehyde .and'm'ea formaldehyde resins.

ganic plasnicizer capable of partially: dissolving the cellulose acetate filamen-issuch as described in Example -I.

" Iilustrationsof other-suitable plasticizers are: glycerol impregnated tow was processed into filter rods in a garnie 'diand t'riacetate, glycerol di and tripropionate, propylene glycol monoand diacetate,- di(methoxyethyl)phthalate, triethyl citrate, acetyl-tricthyl cior'ate and mcthylph'nhalylethyl ,glycollare... 1 5 v Example IV f A how of cellulose acetate-1 yarn containing. approximately 6,000 fibers of five denier per filament was pulled over a compressed air device. which spread out the fibers to a'wi dth of six inches. Whilelihe tow wasin'this spread condition it sprayed'with a mixture consisting of 1 part polyvinyl acetate emulsion (5 5% solids- 45% water), 1, part powdered activated charcoal, and 2ipartswater; The tow was then fed through a cigarette make-up machine which cut and paper wrappediirinto 'rods' 0 158.1

out ro -asix'inclies andsprayed a 10% 50-. r

-1 0 f1 wa rb se. ir

thef ww s l pre o d e hlh' e's i i iw spra r a commerc a available finely divided Iarnpblacki pow: der and ,thenrql led;,back into its original. form. '[he irn pregnated tow was processed into filter rods and the rods I were cut into 15 mm lengths Thefilter tips, containing 9% carbon based onihe weight of the acetate fibers, were attached to standard brandking-size cigarettes shortened by 15 mm. to compensate'for the length ofthefil-ter.

Ten of these cigarettes were smoked on the smoking ma-l chine, The collected smokezwas analyzed -for nicotine and tars. A conrfol'consis'ting of the same brand of cigarettes tipped was filter of the 3 denier perfilame n r tow conraining the adhesive but no lampblack carbon powder was also smoked on the smoking machine and thecollectedsmoke wasanalyzed in the same nannerfor ,n cotinc and tars. l I

mm. diameter and 71 mm. lengths. They were cured by heatiugto 100' C. for BO'minutes. 'Ihedried rods contained 139% activatedjcharcoal -and 2.'1f. 4% 'polyvinyb acetate; They were-then cut into' 1 3-mm. tips; and at tachcd to American king-size cigarette whiclr'had been shortened by 13 mm. Ten filtered cigarettes were smoked cn'a smoking machine similarin design andfioperafion to thejsmoking machine described by J. A. Bradford, W. R. Harlan andH. R. Hammer in Industrial andEngineering Chcmistry, vol'.'28,- pp. 836-9 (1936);: The gaseous'ph'ase of the smoke was collected andana'lyzed for total aide hyde; lfe'n unfiltered cigarettes were smoked, the gaseous analyzed inihe same manner. for use as a control. The filtered'smoke" contained 25 'lcss ald Exem lar f, 1A tow of cellulose with a mixture consisting of l polyvinyl isobutyrafe emulsion (50% solids), 1 partpowdered'acizivated charcoal; and 2 parts water; i The row was processed filter. rips, attached to cigarettes, and analyzed inExample IV. T hc dried rips contained 1!l. 7% polyvinyl isobutyrate and 23.4% acfiuarcd charcoal. 'I hey removed 19% of rhe'aldehydes fromme gaseous phase of cigarette'smoke.

' Example VI I A tow of cellulose acetate yarn: containing approximately 12,000 fibers of five denier per filament was sprayed with a mixture consisting. of 1 part polyvinyl ace tat e,.cn1ulsion1.(55% solids-45% water), 1 part ac; tivated charcoal and 2. parts water. The tow was proc; essed into filter tips, attached to cigarettesandanalyzed as'in Example 'IV.. Thedried tips'co'ntained 13.4% of i polyvinyl acetate end-24.4% activated charcoal. They removed 20% of the aldehydes-from the gaseous phase of cigarette'smoke. l

However, inmost instances I prefer to, employ an orm acetate yarn containing approxi' I mately 6,000 fibers ,of five denier perfilamenc, was sprayed Example VII I A tow of cellulose acetate yarn containing approximately 12,000 fibers of five denier per filament was sprayed with a mixture consisting of 1 part polyvinyl acetate emulsion (55% solids-45% Water) and 2 parts water. The tow was processed into filter tips, attached to cigarettes and analyzed as in Example IV. The tips contained 22.4% polyvinyl acetate. They removed less than 4% of the aldehydes from. cigarette smoke. The pressure drop of these filtered cigarettes was approximately the same as the pressure drop of the filtered cigarettes described in the earlier examples and only slightly higher than that of the unfiltered control cigarettes- Another type of method of applying activated "carbon involves the. use of molten materials such as stearyl alcohol and the like shown in companion copending application Touey et al., Serial No. 701,310. That is, a mixture of a material such as activatedcarbon with melted stearyl alcohol, for example, when sprayed on the fibers, produces a much more efiicient filter than can be made by prior art methods. The presence of the carbon apparently increases the atomization efficiency of the spray head so that finer, sharper particles of the melted material and carbon are produced, and the tendency toward agglomeration is very appreciably reduced. While I preferrto, use an activated carbon in combination with melted stearyl alcphol, stearic acid fatty glycerides, polyoxyethylene or paraffin waxes, it is. also possible to use other solid additives of small particle size to produce. this increase in atomization efficiency with respect to the melter' material. Examples of these other solid powders may be found in silica gel, rice starch, calcium carbonate, and aluminum oxide and aluminum hydroxy stearate. For a more complete understanding of this feature, reference is made to the following examples:

Example VIII Example IX A cellulose acetate tow of 5 denier per filament, 55,500 total denier was sprayed with a mixture of stearyl alcohol and finely powdered activated carbon to give an add-on, based on tow weight, of 22.5% stearyl alcohol and 4.5% carbon. Removals as determined in Examplev VIII averaged 53% for a mm. tip having a pressure drop of 2.7 inches of water.

' Example X A mixture of stearyl alcohol and activated carbon was sprayed on a 2.1 denier per filament, 44,400 total denier acetate tow to give an add-on of 12.5% stearyl alcohol and 2.5% carbon. Removals as determined by Example VIII averaged 48% for a. standard 15 tip having a pressure drop of 2.6 inches of water.

Example XI An acetate tow of 2.1 denier per filament, 44,000 total denier was sprayed with a mixture of stearic acid and activated charcoal to give an add-on of 12.5% stearic acid and 2.5% carbon. When tested in the usual manner, a standard 15 mm. tip gave an average removal of 52% at a 2.7-inch pressure drop.

In carrying out the operation of these methods the type of carbon employed is not a critical factor. Rather, the form of the carbon is more important. The carbon should be in a powdered form so that it can be readily slurried in a liquid or passed through a spraying nozzle.

When tested sions of carbon or graphite may be employed.

- inch and preferably 12 or more crimps.

In the case wherein the carbon powder is dusted on the spread out tow after it has been sprayed with plasticizer, one might wish to increase the. .tackiness of the plasticizer. This can readily be done by dissolving 3 to 20% of certain low molecular weight polymersin the plasticizer before it is sprayed on the tow. j This would create a more tacky surface on the tow which in turn would form a better bond between thecanbon particles and the fiber surfaces. Low molecular weight organic solvent soluble polymers such as polyvinyl acetate, polyvinyl pyrrolidone, and the esters of polyacrylic acid are ideally suited for this purpose. Also, a low viscosity type of organic solvent soluble cellulose ester could be used as a thickener and tackefier for the plasticizer. All of these compounds are readily soluble in the plasticizers already mentioned for cellulose acetate tow filters. 3 They are particularly effective with glycerol diand triacetate. As apparent from the above examples, unusually good results have been obtained with filters prepared from a crimped continuous .filament tow of cellulose acetate fibers sprayed with certain plasticizers in accordance with the preferred embodiments of this invention. However, in the broader aspects of the invention in certain instances the usefulness of the methods extends to other synthetic fibrous filters, including 011086 prepared from fibers of viscose, polyamides and polyesters, where the fibers are are coextensive with the body of the filter.

Some of the methods described above will give filters which will remove a substantial amount of low molecular weight aldehydes from cigarette smoke. It is generally believed that aldehydes such as acetaldehyde and acrolein have a harmful and irritating effect upon the membranes of the throat and mouth; hence it is desirable that their concentration in cigarette smoke be reduced.

In my preferred embodiment and method I apply the additive to continuous crimped cellulose acetate filaments of a total denier within the range of 40,000 to 120,000 and of denier per filament of below 16 and preferably below 5. I have found that the present methods work very well on filaments of a denier of 2-3. The filaments would be crimped, for example at least 8 crimps per The amount, percentage by weight of additive, based on total weight of additive plus weight of filament applied by my meth- The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. The method for the continuous manufacture of tobacco smoke filters which comprises continuously withdrawing crimped continuous tow of synthetic spun filaments from a package of such tow, banding the tow to a width of at least six inches, applying to the banded to'w both bonding agent and powdered additive, reforming the tow thus treated into the desired filter shape and wrapping the filter with a wrapper.

2. A method in accordance with claim 1 wherein the tow consists essentially of cellulose acetate filaments of a denier per filament of less than 8 and of a total denier of less than 120,000.

7 oxyethyDphthalate, triethyl citrate, ac'etyl-tn'ethyl citrate finely dividedcarbon.

4. A method in accordance with claim l'wherein the bonding agent is a latex material essentially comprised .of a polyvinyl-polymeric compound. Y m V f 5. The method for the manufacture of filters from spun =and.mefl1ylphthalylethyl glycoll ate and the additive is filaments-which comprises substantially continuously withdrawing crimped continuous spun cellulose acetate filaments from a package thereof, banding such filamentsto ja width'of at least 8 inches, applying to the banded filaments a molten mixture of a high molecular weight compoundfrom'lthe group consisting of esters, acids and alcohols which'a're normally solid at room temperature but-which are "normally fluid at above 50 C. and which molten high molecular weight compound has incorporated therein acontent of finely divided solid additive, reforming the banded filaments thus treated into the desired filter shape and wrappingxthe periphery of the filter with,

a wrapper.

' 6,. The method in accordance withclaim 5 wherein the additive'is 'finely divided' carbon.

7'. The method in accordance with claim 5 wherein the compound ,is' stearyl alcohol and the finely divided additive is carbon.

8; The method for manufacturing tobacco smoke filters which comprises withdrawing crimped continuous celluloseacetate filaments of a denierperfilament of less than Sand a'totaldenier ofless than "100,000 from a package of such filaments, banding such filaments to a width of at least six inches, applying to the banded filaments both a bonding media and activated carbon particles, the bonding mediab'eing such that it will not materially deactivate 8 i the activated carbon additive, reforming the filaments thus treated into the desired filter shape and applying a wrapper around the circumference of the-filter. i

,9. In a method of making tobacco smoke filters from crimpedcontinuous cellulose acetate filaments wherein the filaments are handed into an opened up condition, the step which comprises spraying the opened up fil aments with an emulsion essentially comprised of a polyvinyl compound from the group consisting of polyvinyl acetate and polyvinylisobutyrate whichpolyvinyl compound has mixed therewith powdered charcoal and water;

References Cited in the fileof this patent UNITED STATES PATENTS 2,3 73,29,6 Donnelly Apr. 10, 1945 2,763,267 Muller Sept. 18, 1956 2,758,913- 'Hiler Oct, 30, 1956 2,774,680 Hackney et a1. Dec. 18, 1956 2,794,239 Crawford et al June 4, 1957 2,794,480 Crawford etial June 4, 1957 Shearer Dec. 10, 1957 

1. THE METHOD FOR THE CONTINOUS MANUFACTURE OF TOBACCO SMOKE FILTERS WHICH COMPRISES CONTINUOUSLY WITHDRAWING CRIMPED CONTINOUS TOW OF SYNTHETIC SPUN FILAMENTS FROM A PACKAGE OF SUCH TOW, BANDED TOW A WIDTH OF AT LEAST SIX INCHES, APPLYING TI THE BANDED TOW BOTH BONDING AGENT AND POWDERED ADDITIVE, REFORMING THE TOW THUS TREATED INTO THE DESIRED FILTER SHAPE AND WRAPPING THE FILTER WITH A WRAPPER. 